1898.] NATURAL SCIENCES OF PHILADELPHIA. 387 



branches are outspread, and the plant becomes mortar-shaped ; when 



dry it rolls up and may preserve this form for years. If again 



wetted it unrolls. 



Abundant on faces and sides of the lava. Pedregal near Tlalpam, 



Aug. 20 (190). 



FILIOES. 



57. Polypodium sp. 



Pedregal near Tlalpam, Aug. 20 (164). 



5G. Notholaena ferruginea Desv. Hook, Sp. Fil. V, 108 ; Eaton Ferns N. Am., I, 

 297 t. 39, figs. 7-10 ; Biol. Centr. Anier. Bot., Ill, 673. 



Texas, New Mexico, Arizona, North and South Mexico, West 

 Indies and Colombia to Chili. 



Bare faces of rocks, pedregal, Aug. 22 (208). 



59. Cheilanthes myriophylla Desv. Hook, Sp. Fil., II, 100, t. 105 A ; Biol. Centr. 



Amer., Ill, 616. 



North and South Mexico reported from several localities and the 

 pedregal by Bourgeau ; in Peru and Chili. 

 Bare rocks, pedregal, Aug. 22 (207). 



GRAMHSTE-ffi. 



60. Bouteloua prostrata Lag. in Varied. Cienc, ii, IV (1805) 141; Gen. et. Sp. 



Nov. 5th; S.Wats, in Proc. Am. Acad., XVIII, 176; Biol. Cent. Am. Bot., 

 Ill, 562. 



" This annual grass is widely distributed from Mexico to Colo- 

 rado, prevailing in bottom land, where it frequently mats the ground 

 but does not seem to be relished by cattle " (Vasey). 



North and South Mexico, Colombia and Ecuador. Pedregal, 

 Aug. 20 (156). 



61. Microchloa setacea R. Brown, Prodr., I, 208; S. Wats., Proc. Amer. Acad., 



XVIII, 176 ; Biol. Centr. Amer. Bot., Ill, 557. 



Reported from North Mexico southward to Bolivia and Brazil. 

 Also in North Australia, tropical Africa and Asia. 

 Hills near Tlalpam, pedregal, Aug. 22 (204). 



CYPERACEJE. 



62. Cyperus seslerioides H. B. K. Nov. Gen. et Sp. I, 209 ; Biol. Centr. Amer. Bot., 



Ill, 451. 



Reported in North and South Mexico, also on the Orinoco. 

 Pedregal, Aug. 22 (196). 



COMMELINACEJE. 



63. Commelina scabra Benth. PI. Hartw., 26; C. B. Clarke in DC. Monogr. Phane- 



rog., Ill, 153 Biol. Centr. Amer. Bot., Ill, 389. 



South Mexico in several places. Pedregal, Aug. 22 (218). 



